Oblique femoral tunnel placement can increase risks of short femoral tunnel and cross-pin protrusion in anterior cruciate ligament reconstruction.
ABSTRACT A more horizontal femoral tunnel has been emphasized for contemporary anterior cruciate ligament (ACL) reconstruction. However, lowering the femoral tunnel may result in a shorter tunnel. In addition, a more horizontally placed femoral tunnel may have inadequate bone stock at the posterior portion of the tunnel, which can lead to protrusion of the cross-pin (Rigidfix) system for femoral fixation.
A more horizontal femoral tunnel position, particularly via the anteromedial (AM) portal technique, will reduce femoral tunnel length, and a more horizontal femoral tunnel position and anterior-to-posterior pin insertion will increase the risk of Rigidfix pin protrusion.
Controlled laboratory study.
In 10 cadaveric knees, we measured maximum lengths of the femoral tunnels at the positions of 11:30, 10:30, and 9:30 o'clock using the transtibial technique and at the 10:30 and 9:30 o'clock using the AM portal technique. Then, for each femoral tunnel via the transtibial technique at 11:30, 10:30, and 9:30 o'clock positions, tests were performed for 3 directions of Rigidfix pin insertion using the lateral epicondyle as an anatomical landmark, namely, 15 degrees anterior to posterior (A-P), neutral, and 15 degrees posterior to anterior (P-A). It was then determined whether pins protruded from the posterior cortex.
The lengths of femoral tunnels produced using the transtibial technique became shorter as the femoral starting position became more horizontal (51.1 mm, 40.0 mm, and 34.2 mm on average at the 11:30, 10:30, and 9:30 o'clock position, respectively). Tunnels made using the AM portal technique were significantly shorter than those made using the transtibial technique: by 7.6 mm at the 10:30 o'clock and 4.5 mm at the 9:30 o'clock positions on average (P < .001). In addition, increasing obliquity increased the likelihood of Rigidfix pin protrusion, especially when pins were inserted in the A-P direction.
The current effort to lower the femoral tunnel position in ACL reconstruction can shorten the tunnel length and compromise the graft fixation at the femur using the Rigidfix system.
When an intended femoral tunnel position is more horizontal than the 10:30 o'clock position for ACL reconstruction, a surgeon needs to be cautious regarding a short femoral tunnel, particularly when using the AM portal technique, and possible protrusion of the cross-pin (Rigidfix) fixator.
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ABSTRACT: Purpose: The object of this study was to evaluate entrance angle effects on femoral tunnel length and cartilage damage during anteromedial portal drilling using three-dimensional computer simulation. Materials and Methods: Data was obtained from an anatomic study performed using 16 cadaveric knees. The anterior cruciate ligament femoral insertion was dissected and the knees were scanned by computer tomography. Tunnels with different of three-dimensional entrance angles were identified using a computer simulation. The effects of different entrance angles on the femoral tunnel length and medial femoral cartilage damage were evaluated. Specifically, tunnel length and distance from the medial femoral condyle to a virtual cylinder of the femoral tunnel were measured. Results: In tunnels drilled at a coronal angle of 45, an axial angle of 45, and a sagittal angle of 45 degrees the mean femoral tunnel length was 39.5 +/- 3.7 mm and the distance between the virtual cylinder of the femoral tunnel and the medial femoral condyle was 9.4 +/- 2.6 mm. The tunnel length at a coronal angle of 30 degrees an axial angle of 60, and a sagittal angle of 45, was 34.0 +/- 12 9 mm and the distance between the virtual cylinder of the tunnel and the medial femoral condyle was 0.7 +/- 1.3 mm, which was significantly shorter than the standard angle (p<0.001). Conclusion: Extremely low and high entrance angles in both of axial plane and coronal plane produced inappropriate tunnel angles, lengths and higher incidence of cartilage damage. We recommend that angles in proximity to standard angles be chosen during femoral tunnel drilling through the anteromedial portal.Yonsei Medical Journal 11/2014; 55(6):1584-91. DOI:10.3349/ymj.2014.55.6.1584 · 1.26 Impact Factor
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ABSTRACT: Purpose Our aim was to evaluate tunnel-graft angle, tunnel length and position and change in graft length between transtibial (30 patients) and anteromedial (30 patients) portal techniques using 3D knee models after anterior cruciate ligament (ACL) reconstruction. Methods The 3D angle between femoral or tibial tunnels and graft at 0 degrees and 90 degrees flexion were compared between groups. We measured tunnel lengths and positions and evaluated the change in graft length from 0 degrees to 90 degrees flexion. Results The 3D angle at the femoral tunnel with graft showed a significant difference between groups at 0 degrees flexion (p = 0.01) but not at 90 degrees flexion (p = 0.12). The 3D angle of the tibial tunnel showed no significant differences between groups. Femoral tunnel length in the transtibial group was significantly longer than in the transportal group (40.7 vs 34.7 mm,), but tibial tunnel length was not. The relative height of the lateral femoral condyle was significantly lower in the transportal than the transtibial group (24.1 % vs 34.4 %). No significant differences were found between groups in terms of tibial tunnel position. The change in graft length also showed no significant difference between groups. Conclusions Even though the transportal technique in ACL reconstruction can place the femoral tunnel in a better anatomical position than the transtibial technique, it has risks of a short femoral tunnel and acute angle at the femoral tunnel. Moreover, there was also no difference in the change of the graft length between groups.International Orthopaedics 08/2014; 38(11). DOI:10.1007/s00264-014-2457-0 · 2.02 Impact Factor
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ABSTRACT: Objetivo Avaliar uma série de pacientes submetidos à cirurgia de reconstrução do ligamento cruzado anterior com tendões flexores pela técnica transportal anteromedial com o uso de Rigidfix para fixação femoral e analisar o posicionamento dos pinos por meio de tomografia. Métodos Foram incluídos no estudo 32 pacientes. A avaliação clínica foi feita com os escores de Lysholm, IKDC subjetivo e Rolimeter. Todos foram submetidos a tomografia computadorizada com reconstrução em 3D para avaliação do ponto de entrada e do posicionamento dos pinos do Rigidfix em relação à cartilagem articular do côndilo lateral do fêmur. Resultados A média do escore de Lysholm obtido foi de 87,81 e do IKDC subjetivo, de 83,72. Dos 32 pacientes avaliados, 43% retornaram a atividades consideradas muito vigorosas, 9% a vigorosas, 37,5% a moderadas e 12,5% a leves. Em 16 pacientes (50%), o ponto de entrada do pino distal do Rigidfix foi localizado fora da cartilagem (extracartilagem), em sete (21,87%) o pino distal lesou a cartilagem articular (intracartilagem) e em nove (28,12%) ficou na borda da cartilagem articular do côndilo lateral do fêmur. Conclusão Os pacientes submetidos à reconstrução do LCA com o sistema Rigidfix pela técnica transportal anteromedial apresentaram um resultado clínico satisfatório no tempo de seguimento avaliado. Entretanto, o risco de lesão da cartilagem articular pelo pino distal do Rigidfix deve ser considerado quando a técnica via portal anteromedial é usada. Outros estudos com maior número de pacientes e com um tempo de seguimento mais longo devem ser feitos para melhor avaliação.11/2014; DOI:10.1016/j.rboe.2014.10.004